<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        function Star(name){
            this.name = name;

        }
        Star.prototype.sing = function(){
            console.log('I can sing');
        }
        /* Star.prototype.sex = 'boy' */
        Object.prototype.sex = 'boy'
        var xtb = new Star('薛天宝');

        console.log(xtb.sex);
    </script>
</body>
</html>